Back to EveryPatent.com
United States Patent |
5,024,064
|
Yonezawa
,   et al.
|
June 18, 1991
|
Method of operating adsorption refrigerator
Abstract
A method of operating an adsorption refrigerator comprising two adsorption
columns each housing therein a solid adsorbent and heat transfer tubes and
sealed with a refrigerant, a condenser, an evaporator, paths for
refrigerant connnecting the adsorption columns to the condenser and
evaporator so that the refrigerant may be circulated through the columns,
and a pipeline equipped with a valve connecting directly the adsorption
columns, which method comprises changing over the adsorption columns
periodically alternately between adsorption and desorption phases in
manner that the one and the other adsorption columns are at opposite
phases and that a heat transfer medium on a heat source side and a coolant
are routed through alternately in response to desorption and adsorption
phases, respectively. Shortly before one cycle of adsorption and
desorption phases is terminated, the paths for refrigerant are shut off
and the valve is opened, the adsorption and desorption phases are further
advanced between the columns while continuing to supply the heat transfer
medium and coolant, thereby to finish the cycle, and subesquently, the
valve is closed to change over to a next cycle of just opposite phases.
Thus refrigeration efficiency is increased.
Inventors:
|
Yonezawa; Yasuo (Nara, JP);
Ohnishi; Toshiya (Sakai, JP);
Okumura; Shin-ichi (Ohtsu, JP);
Sakai; Akiyoshi (Toyonaka, JP);
Nakano; Hiroki (Neyagawa, JP);
Matsushita; Masao (Neyagawa, JP);
Morikawa; Atsushi (Yawata, JP);
Yoshihara; Motoshi (Yawata, JP)
|
Assignee:
|
Nishiyodo Air Conditioner Co., Ltd. (Osaka, JP)
|
Appl. No.:
|
479942 |
Filed:
|
February 14, 1990 |
Foreign Application Priority Data
Current U.S. Class: |
62/106; 62/476; 62/480 |
Intern'l Class: |
F25B 017/00 |
Field of Search: |
62/106,476,480,DIG. 21
|
References Cited
U.S. Patent Documents
4228845 | Oct., 1980 | Cowling | 62/DIG.
|
4594856 | Jun., 1986 | Rothmeyer | 62/112.
|
4610148 | Sep., 1986 | Shelton | 62/106.
|
4637218 | Jan., 1987 | Tchernev | 62/480.
|
4754805 | Jul., 1988 | Rothmeyer | 62/480.
|
4765395 | Aug., 1988 | Paeye et al. | 62/480.
|
Primary Examiner: King; Lloyd L.
Attorney, Agent or Firm: Flynn, Thiel, Boutell & Tanis
Claims
What is claimed is:
1. A method of operating an adsorption refrigerator comprising two
adsorption columns each housing therein a solid adsorbent and heat
transfer tubes and sealed with a refrigerant, a condenser, an evaporator,
and paths for refrigerant interconnecting the adsorption columns to the
condenser and the evaporator so that the refrigerant may be circulated
through the adsorption columns, which method comprises changing over
periodically alternately adsorption and desorption phases between the
adsorption columns in such a manner that the one adsorption column and the
other adsorption column are at mutually different phases and that a heat
transfer medium on a heat source side and a coolant are alternately routed
through the heat transfer tubes of the one adsorption column and the other
adsorption column in response to desorption and adsorption phases; and
further comprises, shortly before one cycle of an adsorption and a
desorption phases is terminated, shutting off the paths for refrigerant;
further advancing the adsorption and desorption phases between the
adsorption columns while continuing to supply the heat transfer medium and
the coolant, thereby to finish the cycle of adsorption and desorption
phases; and subsequently changing-over to a next cycle of just opposite
phases.
2. A method of operating an adsorption refrigerator as set forth in claim
1, which further comprises, after the step of advancing the adsorption and
desorption phases, conducting a preheating step including stopping the
supply of the heat transfer medium and forcing the heat transfer medium
remaining after the desorption in the desorption side column out into the
other adsorption column just before coming into a desorption phase by the
supply of the coolant.
3. A method of operating an adsorption refrigerator comprising two
adsorption columns each housing therein a solid adsorbent and heat
transfer tubes and sealed with a refrigerant, a condenser, an evaporator,
paths for refrigerant interconnecting the adsorption columns to the
condenser and the evaporator so that the refrigerant may be circulated
through the columns, and a pipeline connecting the two adsorption columns
directly to one another and equipped with a valve, the adsorption columns
being adapted to be changed over periodically alternately between an
adsorption and a desorption phases so that the one adsorption column may
be at a different phase from the other adsorption column and that a heat
transfer medium on a heat source side and a coolant may be alternately
routed through the heat transfer tubes of the one adsorption column and
the other adsorption column in response to desorption and adsorption
phases; which method comprises, shortly before one cycle of adsorption and
desorption phases is terminated, sequential steps of : shutting off the
paths for refrigerant and simultaneously opening the valve between the two
columns, further advancing the adsorption and desorption phases between
the adsorption columns while continuing to supply the heat transfer medium
and the coolant until pressure equalization between the two columns is
attained, thereby to finish the cycle of adsorption and desorption phases;
closing the valve; and subsequently changing-over to a next cycle of just
opposite phases.
4. A method of operating an adsorption refrigerator as set forth in claim
3, which further comprises, after the step of advancing the adsorption and
desorption phases, carrying out a preheating step.
5. A method of operating an adsorption refrigerator as set forth in claim
4, wherein the preheating step includes stopping the supply of the heat
transfer medium and forcing the heat transfer medium remaining in the
desorption side column out into the other adsorption column just before
coming into a desorption phase by the supply of the coolant.
6. A method of operating an adsorption refrigerator as set forth in claim
4, which further comprises, shortly before the step of closing the valve,
carrying out a pre heating step including stopping the supply of the heat
transfer medium and driving the heat transfer medium remaining in the
desorption side column out into the other adsorption column just before
coming into a desorption phase by the supply of the coolant.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of operating an adsorption refrigerator
which permits an enhancement of the refrigeration efficiency. More
particularly, the invention is designed to provide a method of operating
an adsorption refrigerator in which two adsorption columns are directly
connected through a pipeline equipped with a valve.
2. Statement of Related Art
Of adsorption refrigerators which avail themselves of adsorption and
desorption actions of a solid adsorbent to and from a refrigerant to
generate cold or to perform heat pump operation, such refrigerators that
take advantage of low-grade heat sources, for example, warm water made
available from solar collectors, etc. (e.g. warm water on the order of
85.degree. C.), or waste heat from works have many advantages that waste
energy otherwise discarded can be harnessed effectively; and that they are
each made up of a smaller number of mobile components such as pumps, which
fact means more economical apparatus cost, and have a smaller operation
noise, as compared with compressor type refrigerators.
The adsorption refrigerators of this type, in general, comprise two sets of
adsorption columns each sealed with a refrigerant and housing therein a
solid adsorbent such as silica gel, zeolite, activated charcoal, activated
alumina, etc. installed in parallel to each other, a condenser and an
evaporator and are systematized so that a heat transfer medium for heating
the adsorbent and cooling water may be supplied alternately to both
adsorption columns to repeat alternately desorption and adsorption phases
whereby refrigerating power output can be continuously obtained.
A problem with such prior art adsorption refrigerators is that shortly
before one cycle of adsorption and desorption phases is changed over
between the adsorption columns, the one adsorption column just having been
at the desorption phase is full of refrigerant vapor driven off from the
solid adsorbent, and, when changed over to an adsorption phase, is
initially obliged to adsorb the remaining refrigerant vapor filled
therein. As a consequence, at an initial stage when a new cycle of
adsorption and desorption phases was started soon after the change-over,
it was difficult to do its inherent work, namely to adsorb the refrigerant
liquid in the evaporator to obtain a required refrigerating power. Thus
the resulting refrigeration power output has been diminished.
The present inventors have already proposed and disclosed a more efficient
operation method for such adsorption refrigeration system in order to
further enhance its refrigeration power output (U.S. Pat. No. 4 594 856).
According to this method, immediately before adsorption and desorption
phases are changed over between two adsorption columns, residual heat such
as warm water remaining within the desorption side column is transferred
to the other adsorption column immediately before coming into a desorption
phase thereby to preheat the solid adsorbent in the latter column,
followed by change-over. This allows to utilize effectively the heat
quantity of the system, but has also encountered the aforesaid problem.
Therefore, with a view toward solving the problem, this invention has been
accomplished and has for an essential object to achieve an enhancement in
refrigeration efficiency of an adsorption refrigerator as stated above in
a procedure that, shortly before one cycle of adsorption and desorption
phases is terminated, comprises shutting off paths for refrigerant and
further advancing the respective adsorption and desorption phases between
two adsorption columns thereby to utilize efficiently refrigerant vapor
filled in the adsorption column and subsequently changing over to a next
cycle of just opposite phases.
Another object of this invention is to provide a method of operating an
adsorption refrigerator meeting both high refrigeration efficiency and a
relatively simple manipulation procedure.
SUMMARY OF THE INVENTION
According to this invention, there is provided a method of operating an
adsorption refrigerator comprising two sets of adsorption columns each
sealed with a refrigerant and housing therein a solid adsorbent and heat
transfer tubes, a condenser, an evaporator and paths for refrigerant
connecting the adsorption columns to the condenser and evaporator so that
the refrigerant may be circulated through vessels of the two columns,
which method comprises changing over periodically alternately between
adsorption and desorption phases so that the one and the other adsorption
columns may be at mutually different phases and a heat transfer medium on
a heat source side for causing a desorption and a coolant for causing an
adsorption may be alternately routed through the heat transfer tubes of
the columns in response to desorption and adsorption phases; and
comprises, shortly before one cycle of adsorption and desorption phases in
the one adsorption column and the other adsorption column, respectively,
is terminated, shutting off the paths for refrigerant, further advancing
the adsorption and desorption phases between the adsorption columns while
continuing to supply the heat transfer medium and coolant thereby to
finish the adsorption and desorption phases, and subsequently changing
over to a next cycle of just opposite phases.
To that end, according to a preferred embodiment, the adsorption
refrigerator is constructed of two adsorption columns each housing therein
a solid adsorbent and heat transfer tubes and sealed with a refrigerant, a
condenser, an evaporator, paths for refrigerant connecting the adsorption
columns to the condenser and evaporator so that the refrigerant may be
circulated through vessels of the adsorption columns, and a pipeline
connecting directly the two adsorption columns and equipped with a valve,
and operated in the following procedure: When one cycle of an adsorption
and a desorption phases comes to an end, namely, each partial pressure of
the refrigerant vapor approaches a constant value in the adsorption
columns, and before it is changed over to a next cycle of just opposite
phases, the transfer of the refrigerant between the one adsorption column
and the evaporator and between the other adsorption column and the
condenser is stopped by any measures, for example, by closing of valves
provided in the paths for refrigerant while the two adsorption columns are
put in communication with each other by opening the valve in the pipeline
connecting the two columns until a pressure equalization between them is
attained, and at the time of the pressure equalization, the valve is
closed, thus finishing substantially completely the adsorption and
desorption phases.
At the time when one cycle of adsorption and desorption phases is being
terminated, the inner pressure of the one adsorption column at the
desorption phase is much higher than that of the other adsorption column
at the adsorption phase because of the desorbed refrigerant vapor in the
former. In that state, all the valves in the paths for refrigerant
connecting the two adsorption columns to the evaporator and condenser are
closed to stop the transfer of the refrigerant, concurrently with which
the valve in the pipeline connecting directly both adsorption columns is
opened. Then, the refrigerant vapor filled in the one adsorption column at
the desorption phase is vigorously transferred, via the pipeline, to the
other adsorption column at the adsorption phase until pressures of both
are equalized. During this step, cooling water is continued to be fed to
the other adsorption column at the adsorption phase and a heat transfer
medium on a heat source side is continued to be fed to the one adsorption
column at the desorption phase, similarly to the aforesaid cycle of the
adsorption and desorption phases, whereby the adsorption, and desorption
phases are further advanced, coincident with the transfer of the
refrigerant vapor. When pressures are equalized between the two adsorption
columns, the valve therebetween is closed thereby to finish one cycle of
the adsorption and desorption step.
According to a preferred embodiment of the method of this invention,
thereafter, residual heat transfer medium such as warm water remaining in
the one desorption side is transferred to the other adsorption side to
preheat it for its subsequent desorption phase. After the preheating step,
a next cycle of just opposite phases is changed over too.
Upon change-over to the next cycle of adsorption and desorption phases in
the one and the other adsorption columns, since the refrigerant vapor
filled in the one adsorption column having finished the desorption phase
was transferred directly to the other adsorption column, the other
adsorption column newly having come into a desorption phase contains a
larger amount of the refrigerant, which means that the desorption of more
refrigerant is enabled, so that a larger amount of refrigerant liquid can
be stored in the condenser and accordingly, can be fed to the evaporator.
On the other hand, the one adsorption column, which is to adsorb the
refrigerant from the evaporator, is decreased in refrigerant gas filling
it, so that its adsorption capacity is increased, being capable of
adsorbing sufficiently the refrigerant from the evaporator.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described hereinbelow in more detail with reference
to the accompanying drawings.
FIG. 1 to FIG. 6 are schematic illustrations of one example of an
adsorption refrigerator to which a method of this invention is applicable,
showing sequential steps when both adsorption and desorption steps in each
adsorption column are performed.
FIG. 1 shows a state in which a first adsorption column is at an adsorption
phase and a second adsorption column, at a desorption phase.
FIG. 2 shows, shortly before one cycle of adsorption and desorption phases
as shown in FIG. 1 is terminated, an advancement step of the adsorption
and desorption phases.
FIG. 3 shows a preheating step to the first adsorption column after the
advancement step.
FIG. 4 shows a changed-over state, just opposite to FIG. 1, when the first
adsorption column is at a desorption phase and the second adsorption
column, at an adsorption phase.
FIG. 5 is similar to FIG. 2, but shows an advancement step of opposite
phases.
FIG. 6 is similar to FIG. 3, but shows a preheating step to the second
adsorption column, subsequently to the advancement step.
FIG. 7 is a graphical representation of a relation between the adsorption
capacity and operation time showing one example of an operation method of
this invention in comparison with a prior art method.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIG. 1 to FIG. 6, one example of an adsorption refrigerator to
which an operation method of this invention is applicable will be
explained.
Throughout the figures, the flow path in which a heat transfer medium or
refrigerant flows is shown in solid lines and the flow path in which no
heat transfer medium and refrigerant flow is shown in broken lines.
In FIGS. 1 to 6, a first and a second adsorption columns 11, 11' each
house, in an evacuated vessel 12, 12', finned tubes 13, 13' which have a
solid adsorbent S such as silica gel, zeolite, activated charcoal,
activated alumina, etc. packed in their fin interstices, and are
interconnected by the provision of a pipeline 10 equipped with a valve
V.sub.5 midway thereof.
Through the finned tubes 13, 13', a warm water which is supplied from a
low-grade heat source, such as solar heat collectors, waste heat from
works, etc. via a heat exchanger or directly, or a cooling water which is
produced in a cooling water producer, such as a cooling tower is
alternately routed.
A condenser 14 is connected to the vessels 12, 12' of the adsorption
columns 11, 11' through ducts 16, 16' equipped with valves V.sub.4,
V.sub.2, and an evaporator 17 is connected to the bottom of a shell 14a of
the condenser 14 via a trap-shaped pipeline 18. The evaporator 17 is
connected, at its casing 17a, to the evacuated vessels 12, 12' of the
first and second adsorption columns 11,11' through ducts 20,20' equipped
midway with valves V.sub.3, V.sub.1. By this piping system, a
predetermined amount of a refrigerant such as water sealed in the
evacuated vessels 12,12' can circulate through the ducts in response to
the opening and closing of the valves V.sub.1, V.sub.2, V.sub.3, V.sub.4.
The condenser 14 houses, in the shell 14a, finned tubes 21, e g. cross-fin
tubes, aero fin tubes, etc., through which cooling water is adapted to be
always routed, so that the refrigerant vapor driven off from the solid
adsorbent S within the adsorption columns 11, 11' may be condensed and
liquefied, collected and stored at the bottom of the shell 14a and
supplied via the pipeline 18 to the evaporator 17.
On the other hand, the evaporator 17 incorporates, in the laterally
elongated casing 17a, heat transfer tubes 22 for passing therethrough a
utilization side heat transfer medium and evaporating dishes (not shown)
located below the heat transfer tubes 22. There, the refrigerant liquid
introduced from the condenser 14 is stored in the evaporating dishes, and
evaporated and gasified on the surfaces of the heat transfer tubes 22 to
take latent heat of evaporation from the utilization side heat transfer
medium, thereby cooling it.
In the Figures, V.sub.11, V.sub.12, V.sub.13, . . . V.sub.21 are valves
provided in pipelines linking the heat transfer tubes 13, 13' of the
adsorption columns 11,11', the heat transfer tubes 21 of the condenser 14,
a cooling water inlet 23, a cooling water outlet 24, a heat transfer
medium inlet 25 on a heat source side, and a heat transfer medium outlet
26 on the heat source side. The valves V.sub.11,V.sub.12, V.sub.13, . . .
V.sub.21 and the aforesaid valves V.sub.1, V.sub.2, . . . , V.sub.5 are
adapted to be operated to open or close sequentially on the basis of
directions of control means (not shown).
The method of this invention will be hereinbelow described of the
refrigerator constructed above.
FIG. 1 shows a step where the first adsorption column 11 is supplied with a
cooling water and performs an adsorption operation whereas the second
adsorption column 11' is supplied with a heat transfer medium on a heat
source side and performs a desorption operation.
That is, the heat transfer medium on the heat source side introduced from
the inlet 25 is admitted through the valve V.sub.16 to the heat transfer
tubes 13' of the second adsorption column 11', where it heats and desorbs
the solid adsorbent S, passes through the valve V.sub.4 and is refluxed
via the outlet 26 for the heat transfer medium on the heat source side, to
the heat source.
The refrigerant vapor heated and desorbed in the second adsorption column
11' is admitted via the valve V.sub.2 to the condenser 14, where it is
cooled and liquefied by cooling water flowing through the heat transfer
tubes 21, collected and stored at the bottom of the shell 14a, and
transferred through the pipeline 18 to the evaporator 17 by reason of
pressure difference, etc.
During this step, the cooling water is admitted to the heat transfer tubes
21 of the condenser 14 and also introduced through the valve V.sub.15 into
the heat transfer tubes 13 in the first adsorption column 11, where the
solid adsorbent S is cooled to adsorb the refrigerant vapor, so that the
refrigerant liquid in the evaporator 17 is evaporated vigorously from the
surfaces of the heat transfer tubes 22 to remove latent heat of
evaporation from the heat transfer medium on the utilization side flowing
through the heat transfer tubes 22, thus cooling it. As a consequence, the
utilization side heat transfer medium thus cooled can be supplied to a fan
coil unit installed at an air conditioning space area, whereby it is
possible to satisfy general temperature conditions of an air conditioning
system (for example, cooling water inlet temperature: 30.degree. C., inlet
temperature of utilization side heat transfer medium: 12.degree. C.,
outlet temperature of it: 7.degree. C.).
In terminating the adsorption and desorption phases of the adsorption
columns 11,11' in the foregoing operation state, the valves V.sub.2,
V.sub.3 and V.sub.5 are switched at one time as shown in FIG. 2 with the
valves V.sub.11, V.sub.12 . . . V.sub.21 remaining unchanged. Then, the
cooling water and the heat transfer medium are still supplied,
respectively, to the first and the second adsorption columns 11,11'
whereas the flow of refrigerant through the adsorption columns 11,11', the
evaporator 17 and the condenser 14 is stopped, and the refrigerant flows
only between the first adsorption column 11 and the second adsorption
column 11', instead.
Here, the second adsorption column 11' is at a high pressure condition,
full of the desorbed refrigerant vapor while the first adsorption column
11 is at a low pressure condition, adsorbing the refrigerant. Hence the
refrigerant vapor blows off, when the valve V.sub.5 is opened, from the
first adsorption column 11 through the pipeline 10 into the second
adsorption column 11', until the pressures of the adsorption columns
11,11' are equalized.
During this step, the cooling water flows through the heat transfer tubes
13 to cool the solid adsorbent S in the first adsorption column 11, thus
adsorbing the refrigerant vapor just shifted whereas the heat transfer
medium on the heat source side flows through the heat transfer tubes 13'
to heat the solid adsorbent S in the second adsorption column 11', thus
expediting the adsorption and assisting the refrigerant vapor in shifting,
whereby the adsorption and desorption phases are further advanced in the
first and the second adsorption columns 11,11', respectively.
The instant that both adsorption columns 11,11' are equalized in pressure
and the adsorption and desorption phases no longer proceed in both
adsorption columns 11,11', the valve V.sub.5 is closed as shown in FIG. 3,
and the adsorption and desorption advancement step is terminated, whereby
one cycle of adsorption and desorption step is finished.
Concurrently, the valves V.sub.11, V.sub.13, V.sub.14, V.sub.15, V.sub.16
and V.sub.19 are switched at one time. Then, a heat transfer medium on a
heat source side introduced from the inlet 25 is directed via the valve
V.sub.13 directly toward the outlet 26 and the supply of it to the second
adsorption column 11' is stopped, and consequently, the heat transfer
medium so far supplied, for example, warm water, remains in the heat
transfer tubes 13' of the second adsorption column 11'. On the other hand,
cooling water is supplied via the valve V.sub.19 to the heat transfer
tubes 13, so that the residual warm water is forced and introduced through
the valve V.sub.11 out into the heat transfer tubes 13 in the first
adsorption column 11, where it is offered for preheating of the solid
adsorbent S just before coming into a desorption phase.
Here, if the operation is further continued, the residual warm water just
introduced in the first adsorption column 11 will be flowed out of the
cooling water outlet 24 side owing to the cooling water supplied to the
second adsorption column 11'. Therefore, the valves V.sub.11, V.sub.12,
V.sub.17, V.sub.18, V.sub.21 are switched as shown in FIG. 4 at such a
timing that permits to avoid the flowing-out and concurrently, the valves
V.sub.1 and V.sub.4 are opened. The heat transfer medium on the heat
source side admitted from the inlet 25 is flowed via the valve V.sub.12
into the heat transfer tubes 13 in the first adsorption column 11 and,
while driving out the residual warm water for preheating the adsorbent
which remains in the heat transfer tubes 13, heads for the heat transfer
medium outlet 26 on the heat source side through the valve V.sub.17.
Consequently, the residual warm water is refluxed to a heat exchanger on
the heat source side, thereby to avoid the loss of heat quantity of the
warm water.
Thus, the first adsorption column 11 comes into a desorption phase after
the preheating step. Prior to the preheating step, the first adsorption
column 11 has a larger amount of the refrigerant adsorbed at the
advancement step for adsorption and desorption as in FIG. 2, so that a
large quantity of refrigerant gas is evolved from the solid adsorbent S
and enters through the valve V.sub.4 and the duct 16' into the condenser
14, where it is condensed and liquified, and transferred to the evaporator
17.
At the same time, the second adsorption column 11' comes into a desorption
phase and is decreased in amount of the refrigerant vapor filled therein
owing to the advancement step for adsorption and desorption as shown in
FIG. 2. Accordingly, the second adsorption column 11' has a capacity
sufficient to liquefy and adsorb a large quantity of the refrigerant
liquid within the evaporator 17 on the solid adsorbent S, thus aiding in
the enhancement of refrigeration efficiency.
Further in reversing the state of the cycle of adsorption and desorption
phases in the second and first adsorption columns 11', 11 to the state
shown in FIG. 1, the same procedure as above is taken, that is, the valves
V.sub.1 and V.sub.4 are closed and the valve V.sub.5 is opened at the
outset, whereby the first adsorption column 11 and the second adsorption
column 11' are put in communication with each other. Then, the refrigerant
gas is transferred from the first adsorption column 11 toward the second
adsorption column 11', thereby to further advance the desorption phase in
the first adsorption column 11 and the adsorption phase in the second
adsorption column 11' (FIG. 5). Thereafter, a preheating step of the
second adsorption column 11' is conducted by the residual warm water
remaining in the first adsorption column 11 (FIG. 6), followed by
change-over of the adsorption and desorption step.
The valve manipulation procedure during these steps is apparent and the
explanation of it will be omitted.
The preheating step to the adsorption column side just before coming into a
desorption phase is usually carried out subsequently to the advancement
step, but, shortly before the advancement step is finished and the valve
V.sub.5 between the two adsorption columns 11,11' is closed, can be
begun, as the case may be.
For the comparison of cooling efficiency between the adsorption
refrigerator operated in accordance with one example of the method of this
invention and a conventional refrigerator which is analogous to that of
this invention except that it has no pipeline 10 interconnecting two
adsorption columns and no valve V.sub.5, comparative tests were carried
out by the use of silica gel and water as adsorbent and refrigerant,
respectively. The results obtained will be shown below.
In the comparison test, each pressure within the first and second
adsorption columns and a pressure within the evaporator were measured to
determine the magnitude of adsorption capacity contributing to the
refrigeration in % by weight.
With the conventional adsorption refrigerator, the pressure values measured
of the one adsorption column on a desorption side, the other adsorption
column on an adsorption side, and the evaporator were 433.3 mmHg, 33.7
mmHg and 7.5 mmHg, respectively. The adsorption capacity (q) was
calculated by the equation:
Desorption Side q.sub.d =0.346 (33.7/433.6).sup.1/1.6 =0.07
Adsorption Side q.sub.a =0.346(7.5/33.7).sup.1/1.6 =0.135
Accordingly, the adsorption capacity contributing to refrigeration is:
(0.135-0.07).times.100=6.5 % by weight.
With the adsorption refrigerator pertaining to this invention, the pressure
of each adsorption column, when pressure equalization between the
adsorption columns was reached by the opening of the valve V.sub.5 before
change-over, was 10.89 mmHg. Accordingly, when one cycle of the adsorption
and desorption step was finished, the adsorption capacity was calculated
as follows:
Desorption Side q'.sub.d =0.346(10.89/433.6).sup.1/1.6 =0.035
.DELTA.q'=0.07-0.035=0.035; 3.5 % by weight
Adsorption Side q'.sub.a =0.346(10.89/33.7).sup.1/1.6 =0.17
.DELTA.q'=0.17-0.135=0.035; 3.5 % by weight
The adsorption capacity participating in the refrigeration is increased by
the amount of .DELTA.q', and accordingly, an adsorption capacity of 10
wt.% can be obtained: 6.5+3.5=10 % by weight.
The relation of the adsorption capacity to operation time is shown in a
graphical representation of FIG. 7, in which each of the bold lines
designates a step during which the adsorption and desorption phases are
further advanced with the valve V.sub.5 opened.
When the conventional adsorption refrigerator was operated in a cycle of
adsorption and desorption steps both of 5.5 minutes, a refrigeration
capacity of 100 RT (R: gas constant, T: absolute temperature) was obtained
whereas in the case where according to this invention the refrigerator was
operated similarly except that the valve V.sub.5 was opened for 1 minute
before the change-over, a refrigeration capacity of 130 RT was obtained,
which means an enhancement of the capacity to 1.3 times.
As described above, when the refrigerator of this invention which has a
pipeline connecting two adsorption columns and a valve equipped midway in
the pipeline is operated in accordance with the method of this invention,
shortly before adsorption and desorption phases are changed over to just
opposite phases, the refrigerant vapor in the adsorption column on the
desorption side can be transferred to the other adsorption column on the
adsorption side, so that the refrigerant vapor that has not heretofore
been offered for the refrigeration can be effectively used, and the
adsorption and desorption step can be further advanced. Hence a
refrigeration efficiency immediately after the change-over can be enhanced
and consequently, an efficient adsorption refrigerator can be provided.
Top